Maximum density mobile storage systems are known in which, as aforesaid, groups of racks are arranged for movement along a bay so as to define a load or unloading gap or space between any two of the racks. So far as the present applicant is aware however, the known system have certain disadvantages which are overcome in the practice of the present invention. More particularly, in certain of these systems control of the movements of the individual racks is governed by segmental bus bars located along the path of travel of the racks and the lengths of the loading or unloading gaps is determined by the length of these bus bars. With such a system change in the length of this gap or space requires changing the lengths of individual bus bars. In others of these systems if, due to different load conditions, or the like, one or more of several moving racks tends to get ahead of some or all of the others, several starting operations may be needed in order to fill up all the thus produced small gaps which, in the moving direction, are beyond the gap or space which is desired to establish.
In accordance with the present invention sensing means are provided which sense the existence of one or a plurality of gaps. If it is desired to establish a gap at a selected side of a selected rack, that rack is started and the sensing mechanism causes that rack and all others ahead of it in the moving direction to continue in motion until all gaps in the moving direction (between racks as well as between the end rack and the end of the bay) are closed, at which time the maximum gap has been established at the selected side of the selected rack and all moving racks are stopped. The length of the bay and consequently the width of the maximum gap can be readily changed simply by moving switch operating means which sense the arrival of the end racks at the corresponding ends of the bay.
Accordingly, objects of the invention are to provide a mobile storage or other system comprising a plurality of movable racks or other load carrying devices in which the width of one or more gaps or spaces between the devices can be varied simply by altering the position of instrumentalities which determine the ends of the bay or other area with which the devices are associated; to provide such a system in which, when placed in motion, the racks in the moving direction remain in motion until all gaps in that direction have been filled or closed; to provide such a system in which the devices are individually controlled and so may be stopped at any time thereby enabling the establishment of one or more gaps in the system; to provide such a system in which controls individual to the several devices may be carried thereon or may be centrally located; to provide such a system having directional priority so as to determine which direction a selected rack tends to move in the event gaps exist on either side thereof; to provide such a system incorporating sensing means to sense the existence of gaps at either side of a selected rack, whereby in the event that rack is started in a selected direction all gaps ahead of it in that direction will be filled before the devices are stopped; and to generally improve and simplify the operation of mobile storage and related systems.